// Copyright 2013 Petar Maymounkov
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package kinfolk

import (
	"fmt"

	"circuit/kit/lang"
	"circuit/use/circuit"
)

type XID struct {
	X  circuit.PermX
	ID lang.ReceiverID
}

func (xid XID) String() string {
	return fmt.Sprintf("%s ==> %s", xid.ID, xid.X.Addr())
}

func (xid XID) IsNil() bool {
	return xid.X == nil
}

// watch returns an equivalent cross-reference to x, which will execute the function r
// each time an invokation to x.Call results in panic.
func watch(x circuit.PermX, recov func(wx circuit.PermX, r interface{})) circuit.PermX {
	return &watchx{PermX: x, r: recov}
}

type watchx struct {
	circuit.PermX
	r func(circuit.PermX, interface{})
}

func (wx *watchx) Call(proc string, in ...interface{}) []interface{} {
	defer func() {
		if r := recover(); r != nil {
			wx.r(wx, r)
		}
	}()
	return wx.PermX.Call(proc, in...)
}
